One of the things that makes Mimi-Rose Howard on Girls so irritating—in addition to her lucrative creative output and no-makeup makeup perfection—is her perfectly executed half-bun. Over recent months, the one part knot, one part half-up style has become the signature look of models and cool girls everywhere, mostly because of its myriad of variations: tightly wound, disheveled and loopy, shiny and spiky, each one as cool and nonchalant as the next. And even though the appeal of this haphazard look lies primarily in the fact that it's supereasy to do, there are a few pointers to keep in mind when taking your half-up hair game to the next level.

To recreate Gwen Stefani's sculptural half-knot, you need to start with a smooth, sleek base. Once you've blow-dried your hair straight and gone over it with a flatiron (prepping with heat-protection spray, of course), separate the top section of hair with a rattail comb, using the arches of your eyebrows as a gauge for how wide the section should be. To ensure clean lines and a spiky knot, tie the elastic really tight when making your ponytail and loop the band around as many times as possible before pulling the tail halfway through, says hairstylist Matt Fugate.

Kate Mara's wavy half-up loop works well for fine hair because it adds volume to the crown. To create the disheveled texture, wrap medium-size sections of hair around a large-barrel curling iron (about one and a half inches), alternating the direction of each wave as you go. Make a center part and section away the top of the hair (everything above the temples basically); but this time, don't create a loop. Instead, pull the hair all the way through to create a ponytail that hits right below the crown of the head. Then roll the ponytail under to form a bun and secure it with bobby pins close to the elastic.

On the half-bun spectrum, Margot Robbie's style is more bun than haphazard loop. "It looks like she spent a little more time on it," says Fugate. To get the look, brush all the hair above your ears straight up to the top of your head and create a tight, high ponytail. Once that's in place, wrap the tail around the elastic to create a knot, pinning the ends in place with bobby pins that match your hair color. A spritz of hair spray keeps flyaways at bay, while a light misting of shine spray ups the glamour factor.

This half-bun is perfect for a blowout that's beginning to deflate. "Day-old hair will add great texture to this look," says hairstylist Ted Gibson. To add lift to your roots (and ensure they won't look greasy by the end of the day), spritz them with dry shampoo. Then take all the hair from the hairline to right above your ears (so all the hair that would be in front of a headband) and gather it into a ponytail right at the crown. Wrap the elastic around your hair tightly but make sure to have some extra slack at the hairline so you get a little bit of height along the forehead. Then all you have to do is wrap the ends into a bun and pin them in place (or, in a pinch, tuck the ends into the elastic).

"This style can also look ridiculous rather quickly," says hairstylist Charles Baker Strahan. "A big sock bun will be a bit Lady Gaga," so stay on the smaller, less perfectly round side of things. To recreate Rihanna's look, pull your hair into a basic half-ponytail, then twist the tail around itself to create a bun. "Just make sure the ponytail holder is hidden by your hair," says Strahan.

You can customize your half-bun to your hair texture. The finer your hair, the more you should pull up into your ponytail to get a substantial bun, says Strahan. If your hair is thicker, like Ariana Grande's, the less you'll need.

Hillary Duff's disheveled texture can be achieved through air-drying or a two-day-old blowout. "Don't do too much to it; the flyaways are what make it look good," says Fugate. To get Duff's knobby knot on your own, take the ends of your half-up ponytail and start twisting so the tail so it becomes ropelike. Then start wrapping the tail around the elastic. Pin in place and mist with some hair spray (but not a lot—you want this to look easy).